There are many applications where it is desirable to employ an amine-cured epoxy resin for bonding, coating, embedding or casting. These applications include the bonding or coating of electrical conductors, the embedding of electrical conductors in the epoxy resin or the casting of epoxy resin with an electrical conductor within. These electrical conductors are typically copper or aluminum. Under many process conditions, however, a surface is formed on the epoxy resin product which is highly corrosive to both copper and aluminum. The problem of corrosive surface formation is particularly acute when aliphatic amines are used as a curing agent. This problem has been previously recognized and determined to be due to the formation of an alkaline surface which includes unreacted amine and unused amine functional groups, either free or in the form of carbonates.
Previous efforts have been made to solve the corrosive surface problem. These efforts have included curing the amine-cured epoxy resin in a dry container at an elevated temperature but the results have not been completely satisfactory. High temperature curing does tend to leave less surface alkalinity but usually is not satisfactory. Moreover, the method may not be practicable in many situations and high temperature curing may have a deletereous effect on the epoxy resin itself because too high a peak exotherm can burn the resin itself or it may destroy any embedded electronic components.